Research suggests that racial disparities in heart disease treatment are due in part to differences in the quality of hospitals used by white and black patients. One possible explanation is that blacks live in neighborhoods with worse hospitals. However, recent studies have found that blacks are also more likely than whites to travel beyond reputable, high quality hospitals, especially for non-urgent specialized treatments, even when they live close to these facilities. Thus, factors other than location may play a role in how blacks and whites use high and low quality hospitals. We assume that, even after accounting for location, black patients are more likely to use lower quality hospital and hospitals that are located in majority black neighborhoods or have a sizable black clientele. This may be the consequence of differences in physician referrals or patient distrust of predominantly white institutions, and is likely to result in higher rates of bypass of high-quality hospitals among blacks. We further assume that the racial differences in how blacks and whites use high and low quality hospitals are more pronounced in metro areas with high residential segregation and in neighborhoods with high social disadvantage. The proposed research will focus on three cardiac conditions with various degrees of acuity - acute myocardial infarction, angioplasty, and coronary artery bypass surgery - and will use several national data sources, including Medicare files to identify patients and hospitals they use; American Hospital Association surveys for hospital characteristics; and the US Census to obtain zip code and metro area demographics and segregation measures. Analyses will employ state-of-the-art methods developed specifically for the study of hospital choice. The study will enhance our understanding of causal pathways in health care disparities by answering important questions related to factors contributing to racial differences in hospital care for the treatment of heart disease. Does geography play a role in black and white seniors' access to high quality hospitals? Is a hospital's neighborhood racial composition particularly salient to black seniors? Are these effects modified by the degree of metro area residential segregation? What is the contribution of differences in geographic access, and of differences in how black and white seniors choose hospitals, to the segregation of health care quality? The proposed study will address these and many more questions. Further, by quantifying the relative roles of geography and hospital choice behavior, the study will provide valuable information to local policy makers aiming to reduce disparities in their respective metro areas.